We present an analysis of anisotropic baryon acoustic oscillations and elucidate how a mis-estimation of the cosmology, which leads to incorrect values of the angular diameter distance, $d_A$, and Hubble parameter, $H$, manifest themselves in changes to the monopole and quadrupole power spectrum of biased tracers of the density field. Previous work has focused on the monopole power spectrum, and shown that the isotropic dilation combination $d_A^2{H}^{-1}$ is robustly constrained by an overall shift in the scale of the baryon feature. We extend this by demonstrating that the quadrupole power spectrum is sensitive to an anisotropic warping mode $d_{A}H$, allowing one to break the degeneracy between $d_A$ and $H$. We describe a method for measuring this warping, explicitly marginalizing over the form of redshift-space distortions. We verify this method on $N$-body simulations and estimate that $d_{A}H$ can be measured with a fractional accuracy of $\sim (3/\sqrt{V})\%$ where the survey volume is estimated in $h^{-3}{\mathrm{Gpc}}^3$.

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